Children's Health

Norovirus: Symptoms and Treatment

Nothing can ruin a vacation like a bout of vomiting, diarrhea, and stomach cramps. Noroviruses have become notorious for sending hundreds of cruise ship passengers at a time running for their respective bathrooms and for steering entire ships back to port early.

Back on dry land, noroviruses also have a big impact on people's health. The CDC estimates that noroviruses are responsible for more than half of all food-borne disease outbreaks each year. And noroviruses are the most common cause of diarrhea in adults and the second most common cause in children.

What Are Noroviruses?

Noroviruses are a group of viruses that cause inflammation of the stomach and large intestine lining (gastroenteritis); they are the leading cause of gastroenteritis in the U.S. The norovirus was originally called the Norwalk virus after the town of Norwalk, Ohio, the location of the first confirmed outbreak in 1972.

Noroviruses are sometimes called food poisoning, because they can be transmitted through food that's been contaminated with the virus. They aren't always the result of food contamination, though. Noroviruses are also sometimes called the stomach flu, although they aren't the influenza virus.

What Causes Infection With Noroviruses?

People become infected with noroviruses when they eat food or drink liquids that have been contaminated; raw or undercooked oysters and raw fruits and vegetables have been implicated in some outbreaks. You can also get infected if you touch an object or surface that has been infected with the virus and then touch your nose, mouth, or eyes.

Noroviruses thrive on cruise ships (as well as in day-care centers, restaurants, nursing homes, and other close quarters) because they are very hardy and highly contagious. They can survive temperature extremes in water and on surfaces.

Once someone is infected from contaminated food, the virus can quickly pass from person to person through shared food or utensils, by shaking hands or through other close contact. People who have a weakened immune system are particularly susceptible to catching noroviruses.

What Are the Symptoms of a Norovirus Infection?

If you come down with a norovirus infection, you'll probably go from being completely healthy to feeling absolutely miserable within a day or two after being exposed to the virus. Typical symptoms include nausea, vomiting (more often in children), watery diarrhea (more often in adults), and stomach cramps.

Other norovirus symptoms include:

• Low-grade fever
• Chills
• Headache
• Muscle aches
• Fatigue

Most of these symptoms aren't serious, but diarrhea and vomiting can deplete your body of the fluid it needs and you can become dehydrated. Children and the elderly are most susceptible to dehydration, as well as malnutrition from not getting enough nutrients.

If you have symptoms of norovirus, your doctor can give you a stool test to confirm that you have the illness. However, norovirus diagnosis is usually made based solely on symptoms.

A small percentage of people who are infected with norovirus never have any symptoms, which suggests they might have some natural protection from the virus.